KR100914819B1 - Congestion control in a wireless mobile system - Google Patents

Abstract

The present invention is dedicated to fast packet data access between a node and a plurality of mobile stations by dedicating a high speed physical downlink shared channel (HS-PDSCH) to all mobile stations (MS-PDSCH) and one associated dedicated channel per each mobile station (MS). A method for improved congestion control in a wireless mobile system in which HSDPA) is established. The method comprises: in the case of congestion, the control device detecting the amount of download data to be continuously downloaded by each mobile station (MS); And based on the amount of download data to be continuously downloaded, the control device releasing an associated dedicated channel (A-DPCH) for the one or more first mobile stations (MS) equal to the amount of data above a predetermined threshold level.

Description

CONGESTION CONTROL IN A WIRELESS MOBILE SYSTEM

The present invention relates to an improved congestion control method in a wireless mobile system and a control device arranged to implement the method. The method is used in a wireless mobile system in which fast packet data access is established between a node and multiple mobile stations by dedicating a high speed physical downlink shared channel to all mobile stations and one associated dedicated channel per each mobile station.

* Abbreviation

3GPP- 3rd Generation Partnership Project (Standard)

A-DPCH-related dedicated physical channel

DL- Downlink

FDD- Frequency Division Duplex

GGSN- Gateway GPRS Support Node

GPRS- Universal Packet Radio System

GSM- Global System for Mobile Communications

HSDPA- High Speed Downlink Packet Access

HS-PDSCH- High Speed Physical Downlink Shared Channel

LLC- Local Link Control

MAC- Medium Access Code

MS- mobile station

PDP-Packet Data Protocol

RLC- Wireless Link Control

RNC- Wireless Network Controller

SGSN-Serving GPRS Support Node

SNDCP- Subnetwork Dependent Convergence Protocol

TCP- transmission control protocol

TDD- Time Division Duplex

UL-uplink

UMTS- Universal Mobile Telecommunication System

UTRAN- UMTS terrestrial radio access network

WCDMA-Wideband Code Division Multiple Access

The Third Generation Partnership Project (3GPP) specification is a standard for third generation mobile telephone systems. The system supports different user data rates for different users. The transmit power used for any user is determined by the interference level in any cell, the user data rate, the channel quality, and the data transmission quality required in the cell.

The control channel and traffic channel are called logical channels. This logical channel is mapped onto the physical channel.

The physical channel may be a wireless broadcasting frequency, a pair of frequencies (including duplex separation) in an analog mobile system, or a time slot on a pair of frequencies in a digital mobile service.

The physical channel may be, for example, a time slot on a particular frequency channel in a TDMA system, a carrier of a logical channel, such as a traffic channel (often abbreviated as TCH), or a carrier of several logical channels, such as various control channels in a multi-frame structure. It can be said.

In TDMA-based digital systems, the mapping process means that time slots and frequencies are assigned to traffic bursts.

Traffic channels carry voice and data (such as Internet traffic) between mobile stations and base stations. Channels are allocated on a call basis.

Typically, time slots are used for only one call (full rate), but an alternative has also been defined with two calls (1/2 rate) per time slot.

All current mobile systems are based on multiple access, which means that all users access the media at the same time. This requires a number of rules to prevent the situation where the mobile phone "everyone talks at the same time." Media, a common resource, must meet the needs of all users.

Traffic channels are assigned via control channel signaling.

Each cell in a cellular system may be considered a separate medium because the mobile phone leaving the cell loses contact with the cell's base station. However, all mobile phones in a cell use the same radio resource, that is, the part of the frequency spectrum that is assigned to the cell.

One technique for channel multiplexing using multiple access is code division multiple access (CDMA). CDMA systems can transmit and receive over the entire frequency band, and a "third dimension" is used to separate, i.e., code, the traffic channel.

A typical feature of CDMA technology is that every mobile phone in the network is assigned a specific code: chip sequence. When a mobile phone wishes to transmit a bit stream, it replaces all bits with its code (for 1) or with the complement of the code (for 0). As a result, depending on the spreading factor used, a number of air interface bits (called "chips") are transmitted per payload bit. If the same modulation method as used for TDMA is used, the required bandwidth will be correspondingly larger. Instead of using tens of kHz for the voice channel, the chip will be modulated over nearly 3.84 MHz. This is why this technique is also called spread spectrum technique.

The mobile telephone system is, for example, a WCDMA system having a downlink transport channel called a high speed downlink shared channel (HS-DSCH) mapped onto a set of physical channels called a high speed physical downlink shared channel (HS-PDSCH). Can be. The HS-DSCH provides enhanced support for interactive, background, and to some extent streaming radio-access-bearer (RAB) services in the downlink direction.

In an HSDPA-enabled WCDMA system (e.g., according to 3GPP Release 5), all users who are provided access to the HS-PDSCH (High Speed Physical Downlink Shared Channel) channel may also use the associated dedicated physical channel (e.g. A-DPCH).

Typical operation in the case of overload (congestion) consists in releasing any channel to reduce the load on certain resources that are lacking, such as DL power, UL interface, DL code, and the like. In particular, all bidirectional / background traffic is carried on the HS-PDSCH and more DL codes need to be made available to handle the sharp increase in interactive traffic (voice, video, etc.), or the A-DPCH is a significant amount In the case that it turns out to consume the power of, it is possible that the A-DPCH is also released.

Current congestion control suppresses downlink information flow in the HS-PDSCH for randomly selected mobile stations by randomly selecting the A-DPCH to be released for any mobile station. This results in a situation in which a user who has almost finished downloading is taken out of the system by a user just entering the system. As an end user, this can be very cumbersome, especially if the application provides some kind of indication of the progress of the download (in one case it might be interrupted after seeing the download complete 95% complete). ).

Therefore, there is a need for improved congestion control in HSDPA based systems and the like, with enhanced data transmission flow control to make the user more satisfied.

1 is a schematic diagram of a TCP / IP based network in a GPRS standard in accordance with an embodiment of the present invention;

FIG. 2 is a schematic of several stacked protocols of GGSN to SGSN over Gn interface and SGSN to MS over Iu interface. FIG.

3 is a graph of buffer versus time.

The present invention aims to solve the above problem by an improved congestion control method and a control device arranged to perform the method.

The method provides high speed packet data access (HSDPA) between a node and multiple mobile stations by dedicating a high speed physical downlink shared channel (HS-PDSCH) to all mobile stations (MS-PDSCH) and one associated dedicated channel per each mobile station (MS). Is used in the wireless mobile system in which is set. The HSDPA setting may be performed by a node.

The method is as follows:

In case of congestion, the control device detecting the amount of download data to be continuously downloaded by each mobile station MS; And

Based on the amount of download data to be continuously downloaded, the control device releasing an associated dedicated channel (A-DPCH) for at least one first mobile station (MS) having a data amount above a predetermined threshold level.

The advantage of the present invention is that instead of the prior art, which randomly deviates regardless of state, the mobile station which has almost finished downloading completes the download.

In one embodiment of the invention, the threshold level is the amount of downlink data to be downloaded by one or more second mobile stations (MS) using the same high speed physical downlink shared channel (HS-PDSCH) as the first mobile station (s). to be. In this embodiment, the threshold is set to release the A-DPCH by comparing all mobile stations and at least for one or several user units with more data to be downloaded than other mobile stations. The comparison may provide a hierarchy with a mobile station having the most data to be downloaded at the top and a mobile station having the least data at the bottom. The threshold may be a floating value that is always set at the mobile station having the second most data to download, ie there are not two mobile stations in the hierarchy. The advantage here is that the mobile station with most of the data to continue downloading will be out of the first round, and if more resources have to be released, the next one will be released sequentially during the next round, while all other mobile stations will continue downloading, The mobile station with the minimum data for it is given the opportunity to complete the download. The threshold level may also be set to a level that represents a particular mobile station in the hierarchy, and all mobile stations above the mobile station in the hierarchy may experience the release of the associated A-DPCH.

In one embodiment of the invention, the threshold level is a preset value, for example, all mobile stations that have downloaded more than the intended amount of any percentage may continue, and other mobile stations may experience release of the associated A-DPCH. .

The wireless mobile system can be a WCDMA based system, where the node is an RNC. However, the present invention is applicable, for example, to all systems using an associated dedicated channel and a downlink shared channel that always consume a significant amount of total system resources for control information. As mentioned in the prior art description, the HS-DPSCH and A-DPCH relate to a WCDMA system, but the present invention is applicable to, for example, CDMA 2000 1x, EVD (EVolution Date Only) and EVD (Volution Data / Voice). Where the HS-DPSCH is denoted F-FDCH (forward link packet data channel) and the corresponding A-DPCH is denoted as F-FCH (forward link basic channel). CDMA 2000 relates to 3GPP2 and EVDO, and EVDV corresponds to HSDPA system in 3GPP3-based WCDMA system. The present invention may also be used in any other FDMA and / or TDMA based system having a channel structure similar to WCDMA or CDMA 2000.

In one embodiment, the threshold level is a preset value of data that has not yet been confirmed in RLC and RNC. Data that has not yet been identified can be detected by checking in the RLC buffer, where it will be possible to find a user with a small amount of unconfirmed data. The threshold can then be defined in bytes. The most direct way to use this information is to define a threshold so that mobile stations with data remaining less than this threshold are protected at least in the first round of releasing the A-DPCH.

If there is a proxy in the RNC, the information from the proxy can be passed through the RNC internal interface to the radio resource management function in the control device that determines which A-DPCH is released. The radio resource management function is preferably part of the RNC.

It would of course also be possible to combine this criterion with other criteria, such as the detection of power usage of individual radio links. Data that has not yet been identified can also be used for the above-described comparisons among the various mobile stations.

Therefore, the basic idea of the present invention is to search / detect users with very little data waiting for transmission, and the advantage is that the end to wireless data service in WCDMA or other similar system using HSDPA-enabled network or HSDPA-like network. The user experience is improved.

In principle, the same mechanism can also be considered for bidirectional or background traffic on a dedicated channel, but the gain is assumed to be lower.

The invention also provides a high speed physical downlink shared channel (HS-PDSCH) per node and each mobile station (HSDPA) dedicated to all mobile stations (HSDPA) between the node and multiple mobile stations (MS). A control device for improved congestion control in a wireless mobile system set up by one dedicated dedicated channel (A-DPCH),

In case of congestion, the control device is arranged to detect the amount of download to be continued to be downloaded by each mobile station MS,

Improved congestion arranged to release an associated dedicated channel (A-DPCH) for one or more first mobile stations (MS) with more data than a predetermined threshold level, based on the amount of download data to be continuously downloaded. A control apparatus for control is provided.

All the above mentioned advantages of the method are also valid for the control device.

The control device is preferably part of the RNC and can be arranged to carry out all the above described method steps.

The invention will now be described in detail with reference to a number of figures.

Figure 1 schematically illustrates a TCP / IP based network in the GPRS standard according to one embodiment of the present invention. The network includes a landline based network and a wireless network. Terrestrial-based networks include hosts in the form of SERVER, GGSN and SGSN. The wireless network includes clients in the form of RNC, NodeB and MS, all based on WCDMA (see Figure 2). The interface between GGSN and SGSN is called Gn, and the interface between SGSN and RNC is called Iu. The interface between the MS and the Node-B in the second wireless network is called Uv. The interface between GGSN and SERVER is called Gi.

When discussing FIG. 1, FIG. 2 is cross-referenced. Figure 2 schematically illustrates the various stacked protocols of GGSN to SGSN over Gn interface and SGSN to MS over Iu interface. In FIG. 3, the UTRAN is related to the RNC and Node-B in FIG.

The GGSN is related to a gateway GPRS support node that acts as an interface between the GPRS backbone network and external packet data networks (wireless networks and IP networks). This converts the GPRS packets from the SGSN into a suitable packet data protocol (PDP) format (eg IP) and sends them to the corresponding packet data network. In the other direction, the PDP address of the incoming data packet is translated into the GSM address of the destination user. The readdressed packet is sent to the trusted SGSN. To do this, the GGSN stores the user's current SGSN address and the user's profile in his location register. GGSN can also perform authentication and payment functions for external systems, while SGSN can perform authentication.

The function of the SGSN is a router at the interface between a wireless network and a landline based network, and has been described above.

WCDMA technology is used for the UTRAN air interface. UMTS WCDMA is a direct sequence CDMA system in which user data is multiplied by quasi-random bits derived from the WCDMA spreading code. In UMTS, in addition to channelization, code is used for synchronization and scrambling. WCDMA has two basic modes of operation: frequency division duplex (FDD) and time division duplex (TDD).

Node-B features:

Wireless interface transmit / receive

Modulation / demodulation

CDMA physical channel coding

Micro diversity

Error handling

Closed loop power control.

RNC features include:

Wireless resource control

Approval control

Channel assignment

Power control setting

Handover Control

· Clock Diversity

·encryption

Segmentation / Reassembly

Broadcast signaling

Open loop power control.

At the air interface Iu at the RNC for UMTS GPRS, concentration is performed at the air interface Iu because the number of traffic channels is limited.

The present invention relates to a congestion control method in which a dedicated channel (A-DPCH) is released for a particular mobile station. Such mobile stations have an amount of information to download above a set threshold level. To find such a mobile station, the search for a mobile station below the threshold level indicates a mobile station that will not be released, but not at least in the first classification round. By examining the RLC buffer in the RNC (see, for example, Figures 2 and 3), it is possible to find a mobile station with a small amount of unconfirmed data, which is a signal that the mobile station has downloaded the main part of the information. Should be prioritized and should not be released by releasing the A-DPCH corresponding to the mobile station if there is another mobile station with a larger amount of unconfirmed data.

If there is a proxy in the RNC, information from this proxy can be passed to the radio resource management function through any RNC internal interface. Proxies are often proposed as a means of hiding a wireless network from an application by intermediate buffering of data.

3 shows a graph of buffer versus time in RLC for data that has not yet been identified. The amount of data not yet verified increases significantly in the first part of the download process and then decreases to zero. In Fig. 3, the threshold is set at a predetermined level. All mobile stations (MS) with data not yet identified above the threshold are dropped by canceling the corresponding A-DPCH for that user. As can be seen in Fig. 3, the mobile station which has just started downloading is also lower than the threshold and will not go out. This is of course not the desired state, but data that has not yet been confirmed will grow very quickly and the mobile station will be one of the mobile stations above the threshold level at high speed, resulting in the release of the corresponding A-DPCH.

Claims (10)

High speed between the node and multiple mobile stations (MS) by dedicating a high speed physical downlink shared channel (HS-PDSCH) to all mobile stations (MS-PDSCH) and one associated dedicated channel (A-DPCH) per mobile station (MS). An improved congestion control method in a wireless mobile system in which packet data access (HSDPA) is established, In the case of congestion, the control device detecting the amount of download data to be continuously downloaded by each of the mobile stations MS, and Based on the amount of the download data to be continuously downloaded, the control device releasing the associated dedicated channel (A-DPCH) for at least one first mobile station (MS) having a data amount above a predetermined threshold level. Improved congestion control method in a wireless mobile system comprising a. The method of claim 1, The threshold level is an amount of download data to be downloaded by one or more second mobile stations (MS) using the same high speed physical downlink shared channel (HS-PDSCH) as the first mobile station (s) MS. Improved congestion control method in a wireless mobile system characterized by. The method of claim 1, Improved congestion control method in a wireless mobile system, characterized in that the threshold level is a preset value. The method of claim 1, And wherein said threshold level is a preset value of data not yet identified in RLC. The method according to any one of claims 1 to 4, And wherein said node is a WCDMA based system and said node is an RNC comprising said control device. A high speed physical downlink shared channel (HS-PDSCH) dedicated to all mobile stations (HSDPA) between a node and multiple mobile stations (MS) and one associated dedicated for each mobile station (MS) A control apparatus for improved congestion control in a wireless mobile system set by a dedicated channel (A-DPCH), In case of congestion, the control device is arranged to detect the amount of download data to be continuously downloaded by each of the mobile stations MS, The control device is arranged to release the associated dedicated channel (A-DPCH) for one or more first mobile stations (MS) having a data amount above a predetermined threshold level based on the amount of the download data to be continuously downloaded. A control device for improved congestion control. The method of claim 6, The threshold level is an amount of download data to be downloaded by one or more second mobile stations (MS) using the same high speed physical downlink shared channel (HS-PDSCH) as the first mobile station (s) MS. Control unit for improved congestion control. The method of claim 6, And the threshold level is a preset value. The method of claim 6, And said threshold level is a preset value of data not yet identified in RLC. The method according to any one of claims 6 to 9, And wherein said wireless mobile system is a WCDMA based system and said node is an RNC.